Power for the horn comes from the TIPM (totally integrated power module) under the hood; there's no separate fuse for the horn itself. You may want to check fuse #30 under the hood but if that's out I'd expect a lot more than the horn to not be working.

The circuit for the horn switches goes through the steering column control module. It's possible you have bad switches like Rainman said or the connector to/from the SCCM could be loose.

If you haven't been doing any work with the steering wheel, I'd let the warranty cover this one.